In theory, drinking 14 units a week will ultimately give you a 1% chance of dying of an alcohol-related condition.

But a new study has found that what is considered a "safe" drinking level varies enormously around the world.

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The research is by psychologists at Stanford University in the US, and published in the medical journal Addiction.

They looked at the drinking recommendations of 75 countries, and found that 38 of them had no guidelines at all – and the "safe" limit in some countries is four times higher than in others.

The various countries don't even agree what a "drink" is.

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The World Health Organisation (WHO) defines a "standard drink" as containing 10ml of pure alcohol. That's equivalent to 250ml (about half a pint) of 4% beer, 75ml (about half a small glass) of 13% wine, or one 25ml shot of 40% spirits.

But if you go to Austria, a "drink" is defined as twice as much – 20ml of pure alcohol. Here in the UK, it's just 8ml of alcohol. In Canada and the US, it's 14.

Others, such as South Africa, couch their advice in terms of how many glasses of beer or wine you should have per day, but don't say how big those glasses are.

It gets even more confusing when you start looking at how many of those drinks each country says you can safely drink a day.

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The WHO recommends no more than two standard drinks a day for anyone, male or female.

But Chile and the USA both say that, for men, four drinks are the "low risk" limit – and their "drinks" are 14ml of alcohol, so the total "low risk" level of alcohol is 56ml, almost three times the WHO's recommendations.

It's worth noting, say the authors, that "the US government, rather confusingly, has guidelines for low-risk drinking … yet also has a separate, lower guideline for ‘moderate drinking’".

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The differences are even more dramatic when you look at recommended guidelines for women.

Sweden, along with Bosnia and Herzegovina, Croatia, India, Portugal, and Slovenia, recommend that women drink no more than 10ml of alcohol a day, half the WHO guidelines – but the USA and Chile think 42ml is low risk, more than four times Sweden's level.

What's more, some nations have different recommendations for men and women, while others (and the WHO) think they should have the same limits.

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Britain, Australia, Germany, South Africa, and Portugal all give the same recommended limits for men and women, although those limits vary. Other countries' recommendations for men can be as much as twice as high as those for women. For instance, Estonia suggests women drink no more than 20ml of alcohol, while men can have up to 40ml.

Others say that you're allowed to drink more on "special occasions".

Australia, Canada, Denmark, Fiji, France, Mexico, New Zealand, Poland, and the United Kingdom all say it's OK to break the usual limits on weddings and bar mitzvahs.

The study says the confusion may arise from the fact that the different countries are looking at different data to establish their recommendations.

It also says that "there is no robust evidence that the general population changes its level of alcohol consumption in response to governments defining standard drinks and publishing low-risk drinking guidelines", so these limits may not make much difference anyway.